The invention relates generally to a cassette for photosensitive material.
More particularly, the invention relates to a cassette for accommodating a sheet of x-ray film.
A known cassette for accommodating a sheet of x-ray film has a pair of cooperating members which are movable between an open position, and a closed position in which the members define a closed compartment for the film. Locking elements are provided to arrest the cooperating members in the closed position. A flexible magnetic sheet is secured to one of the members and has a size which is the same or approximately the same as that of the film compartment or the sheet of film. A ferro-magnetic foil which cooperates with the magnetic sheet is mounted on the other of the cooperating members. The magnetic foil is mounted on the respective member by means of a connecting element which permits the magnetic foil to move a limited amount relative to the member. One or more fluorescent or intensifying screens are provided and are located adjacent to the film in the closed position of the cassette. The magnetic sheet and magnetic foil, which are attracted to one another, flank the film and the intensifying screen or screens. The force of attraction between the magnetic sheet and the magnetic foil urges the intensifying screen or screens into firm engagement with the film.
A cassette of the type outlined above is disclosed in the German Offenlegungsschrift No. 29 17 547. In this cassette, the member which supports the magnetic foil is provided with a strip of foamed material which extends circumferentially of the member. The magnetic foil is adhesively secured to the foamed strip and the latter constitutes the connecting element via which the magnetic foil is mounted on the respective cassette member for movement relative thereto The magnetic foil can undergo limited movement in a direction normal to the cassette member as well as in directions parallel to the member. Limited movement of the magnetic sheet or magnetic foil relative to the respective cassette member is necessary in a cassette of the type which employs a pair of magnetic elements to urge the intensifying screen or screens into engagement with the film. This stems from the fact that the cooperating members of the cassette are somewhat flexible and may undergo some deformation when the cassette is opened and closed. By mounting the magnetic sheet or the magnetic foil for movement relative to the respective cassette member, the magnetic sheet or magnetic foil can adjust to deformation of the cassette members. This so-called "floating suspension" of the magnetic sheet or magnetic foil is also useful in compensating for differences in the coefficient of thermal expansion of the cassette members, the magnetic sheet or magnetic foil and the intensifying screen or screens.
It has been found that the connecting element in the known cassette does not permit the magnetic sheet or magnetic foil to undergo sufficient movement relative to the respective cassette member in a direction perpendicular to the latter. This can result in damage to the movably mounted magnetic foil or magnetic sheet.